If 2 over 7 of a ton of concrete covers 7 over 8 of a wall, how many tons of concrete are required to cover the entire wall?

Set up a proportion:

2/7/7/8 = x/1

Multiply 1 to both sides:

(2/7 * 1)/(7/8) = x

(2/7)/(7/8) = x

Flip the 2nd fraction and multiply:

2/7 * 8/7

Multiply the numerators and denominators together:

16/49

So 16/49 tons of concrete are required to cover the entire wall.

Cthe residual plot for model 1 has a non random pattern and is a good fit for the data